JPH02256200A - Plasma generator with module split cathode - Google Patents

Abstract

PURPOSE:To obtain a plasma generator easily generating a large output by constituting it with a common anode and multiple cathodes arranged to surround the anode. CONSTITUTION:A plasma generating source 46 is constituted of individual plasma power sources 99A, 99B and 99C, and they are connected to cathode assemblies 84, 86 and 88 respectively. The plasma power sources 99A, 99B and 99C have individual DC power sources, an anode terminal is connected to an anode located in a gun main body 70, and cathode terminals are connected to mating cathode assemblies 84, 86 and 88 respectively. The plasma power sources 99A, 99B and 99C can be independently power-adjusted, thus the power fed to the cathode assemblies 84, 86 and 88 can be independently changed. Outputs of the cathodes 84, 86 and 88 and the anode can be independently controlled, the total output is easily increased, and a stable large output can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plasma device that generates a supersonic plasma jet, and particularly to a plasma generator that has a plurality of cathodes and a common anode. It is something.

[Conventional technology]

A plasma device that generates a supersonic plasma jet is disclosed in U.S. Patent No. 3.839.618 (October 1974).
'Method and Appara (published on the 1st of each month)
tus for Bfecting High-En
Ergy Dynamic Coating of 5
A plasma jet is obtained by flowing an inert gas between electrodes, as seen in "Ubstrates".This plasma jet forms a transitional arc with an appropriate distance between the plasma generator (plasma gun) and the target. It is used to form a film on an object by heating the object or by putting powdered raw material into the gun.

Furthermore, the gun and object are used in a chamber whose pressure is reduced by a vacuum pump, etc. Under reduced pressure, the plasma jet becomes a supersonic flow, and various applications have been attempted using this supersonic plasma generator.

Furthermore, U.S. Patent No. 4.328.257 (May 1982)
11 System and Method (released on April 4th)
d for Plasma Coating”, the plasma gun and the object are housed in a vacuum chamber, a DC power source is electrically connected between the plasma gun and the object, and the plasma gun has a motion mechanism that allows it to make various movements. Raw material powder such as metal is fed into a plasma gun and sprayed onto the object to form a film.Also, since these processes are performed under reduced pressure, filters and heat exchangers are attached to the vacuum chamber. equipment, vacuum pumps, etc. However, the plasma gun in this case consists of a conventional pair of anode and cathode.

In addition, the polarity of the DC power supply connecting the plasma gun and the object described above can be switched depending on the situation.

An example of having two or more cathodes and a common anode is
No. 1-7556 "Plasma Gun", JP-A-61-230
No. 300 "Plasma arc torch" can be seen.

All of these are designed to operate in the atmospheric atmosphere, and are not designed to generate supersonic plasma under reduced pressure as described above. Having multiple cathodes complicates the structure of the gun and also makes it very difficult to optimize operating conditions.

[Problem to be solved by the invention]

In thermal spraying, which uses a plasma generator to inject raw material powder such as metal to form a film, a conventional pair of anodes,
When using a cathode, the raw material powder must be introduced from the side of the plasma jet flow due to its structure, so it is an important issue to efficiently introduce the raw material powder into the high temperature, high flow rate part at the center of the plasma jet. there were. This was because some particles were repelled by the plasma jet or penetrated by the plasma jet due to differences in particle size and specific gravity of the raw material powder.

In addition, a method in which a plurality of cathodes are provided and raw material powder is introduced from above the center of the anode in the plasma jet axis direction requires a complicated structure of the plasma generator, and it takes time to replace the cathode, anode, etc. when they become worn out.

Furthermore, it was difficult to ensure a sufficient heat transfer area for water cooling piping for cooling the electrodes.

Furthermore, there was the problem that when the raw material powder was introduced, the molten powder scattered in the anode space (arc chamber) would adhere to it, making it difficult to optimize stable plasma operating conditions for a long period of time, which was a technical problem.

[Means for Solving the Problems] In order to solve the problems described in the previous section, the present invention operates the plasma gun and the object in a reduced pressure atmosphere in a vacuum chamber, and uses a stable supersonic plasma jet. Execute the desired action. Moreover, each of the plurality of cathodes is divided into modules and has a structure that allows for easy removal and disassembly. Therefore, by replacing each modularized cathode, the plasma inflow angle to the anode, discharge distance (arc gap), and cathode tip shape can be adjusted, improving the degree of freedom in controlling plasma operating conditions.

Next, the anode has a nozzle shape extending from the central space (arc chamber) to the outlet, and is configured to produce a stable supersonic plasma jet under reduced pressure.

Injection of raw material powder from above the arc chamber is performed via a sleeve-shaped part (powder input tube), and by replacing this sleeve, the diameter of the input tube can be selected and the pattern of inputting the raw material powder into the arc chamber can be changed. Can be controlled. Furthermore, by branching the hole near the outlet of the input tube and directing the outlet direction of each branch hole toward each cathode, the raw material powder can be inputted into the high temperature part of the plasma jet, resulting in high-melting point materials and difficult-to-melt materials. This makes it possible to easily melt and form a dense film.

As mentioned earlier, the problem of adhesion of raw material powder inside the arc chamber is caused by
The anodes have a structure that allows them to be removed individually and disassembled easily, which greatly improves maintainability, and the freedom of selection of these has also been improved, making it possible to avoid adhesion inside the arc chamber. Combinations and operating conditions can be selected.

Cooling of the high heat load parts of each cathode and anode greatly affects the life of the device, but in the present invention, a cooling water system that cools each cathode,
It has a separate cooling water system to cool the anode, forming a water cooling structure that provides sufficient cooling.

In particular, for the anode, multiple cooling water holes penetrate between each cathode section from the bottom to the top, and at the top of the anode, a special lamp designed to surround the powder feeding tube allows cooling water to swirl efficiently at the top of the anode. It has a cooling structure. As a result, compared to conventional plasma generators, the output of each cathode and anode can be controlled independently, and combined with the ability to easily increase the total output, the plasma generator is capable of stably increasing output.

〔Example〕

Examples are shown in FIGS. 1 to 33 to specifically explain the features of the present invention.

FIG. 1 shows a plasma system according to the invention.

The plasma system includes a plasma chamber 10 that is sealed to maintain a vacuum and is an insulating container with a pressure-resistant structure.
Contains. This vacuum chamber 10 is composed of a cylindrical main body portion 12 and an upper lid 13 connected thereto.

The cylindrical part 12, which is part of the plasma chamber 10, is guided by and connected to a device for treating the gases and particles in the chamber and for maintaining the desired atmospheric pressure, including a lower collector conical lid. Contains 14.

The plasma spray in the downward direction is generated by a plasma gun 16 mounted inside the upper lid 13, and the position of the plasma gun 16 is controlled by a plasma gun operating mechanism 18. Each of the vacuum chambers 10 is constructed as a double-walled cooling structure, and the upper lid 13 is removable for accessing the internal operating equipment. A plasma gun operating mechanism 18 supports and controls the plasma gun 16 through bearings and connections sealed within the wall of the top cover 13.

The powder supply mechanism, which is also connected to the top lid 13, has the function of controlling and introducing heated powder during plasma spraying through a flexible tube connected to the plasma gun 16.

The downward plasma stream impinges on the process component 24, which is supported in an internally cooled conductive process component holder 25. Moreover, this processing part holder 25 is attached to the chamber 1.
2 to an external process component movement mechanism 26 for alignment and movement during operation.

A dummy processing component or dummy sting 28 is disposed proximate one end of the processing component 24 but separate from the processing component 24, and the dummy sting 28 is also internally water cooled and passes through the side wall of the chamber 12 to a dummy swing motion mechanism 30. is connected to. Because the processing component holder 25 and the dummy swing 28 can be adjusted to their inserted positions relative to the central axis of the chamber 10, and because they are constructed of electrical conductors, they can be selected for transitional arc generation in various operating conditions. Can be kept on electricity.

The collector cone lid 14 below the processing part 24 and the dummy swing 28 is connected to a baffle filter module 32 for introducing overspray (unattached particles and gases); It has a water-cooled baffle for cooling and a filter to remove most of the introduced particles.

The fluid passing through the baffle filter module 32 is
It passes through a heat exchanger 36 equipped with a cooling device and into a vacuum manifold 38 equipped with an overspray collection filter 40 that removes substantially all remaining particles in the fluid. Vacuum manifold 38 is connected to a vacuum pump 42 having sufficient capacity to maintain the atmospheric pressure within chamber 10 at a predetermined pressure.

Typically, this atmospheric pressure is between 0.6 and 0.001 atmospheres. Baffle filter module 32 and heat exchanger 3
6 preferably has a double-walled cooling structure similar to the overspray recovery filter, but it is also possible to use the type used in ordinary plasma equipment. The entire system can be mounted on rollers and moved on tracks so that it can be easily manipulated and the parts can be used separately. Not shown are the insulated feed-through plates that make electrical connections to the conventional viewing window and water-cooled operating door. Processing component holding and motion control equipment is attached to the hinged door 43 of the chamber 12.

Electrical energy is supplied to the operating section of the device through a fixed bus bar 44 attached to the top of the top cover 13. A flexible water-cooled cable connects an external plasma power source 46 and a high frequency power source 48 to the plasma gun 16 for generating a plasma jet through a bus bar 44. Plasma power supply 46 generates the necessary potential difference between the electrodes of plasma gun 16 and between plasma gun 16 and processing component 24(7)ftJi. As is well known, the high frequency power source 48 is used to initially ignite the transferred plasma arc by superimposing a high frequency voltage on the plasma power source DC voltage. The polarity variable transition arc power supply 50 is
It is connected to the plasma gun 16, processing component holder 25, and dummy sting 28 through a bus bar 44. U.S. Pat. No. 43 by Muehlberger et al., mentioned at the outset.
28,257, the transitional arc power supply 50 can also generate a reverse polarity transitional plasma arc between the plasma gun 16 and the workpiece 24.

In order to operate the plasma gun 16, a cooling water boost pump 52 is used to create an appropriate flow of cooling water inside the plasma gun 16 as will be described later. A plasma gas source 54 provides a suitable ionized gas for generation of the plasma jet.

The plasma gas used here is argon alone or argon gas containing helium or hydrogen, but other gases known to those skilled in the art can also be used.

The sequence of controls and speeds and amplitudes of the various operating mechanisms of the apparatus of FIG. 1 are coordinated by a system control console 56. Plasma gun 16 is operated separately under the direction of plasma control console 58. The functions performed by these consoles and the circuitry contained therein are readily understood and are not shown in the figures or described in detail here.

The transition arc control circuit 60 performs control to switch the polarity of the transition arc.

Except for the plasma gun 16, which uses a split cathode, the rest of FIG.
The plasma device is identical to that described in US Pat. No. 4,328,257 to Erger et al.

FIG. 2 shows the plasma gun 16 of FIG.

The plasma gun 16 includes a gun body 70 which is generally cylindrical in shape and houses an anode and a cooling device equipped with a powder injection device as described below. Powder or other material to be sprayed is introduced into the plasma gun 16 through a powder introduction tube 72 that passes through an anode stop plate 74 at the top of the body 70.

The cooling water boost pump 52 is connected to the gun body 7 of the plasma gun 16.
0 and supplies cooling water to the anode cooling system located within the main body 70.

The water-cooled boost pump 52 is connected to the plasma gun 16 by two of the tubes exiting from its top. These two tubes are supplied with cooling water by connections 76, 78 attached to the anode stop plate 74.

The cooling water that has passed through the anode cooling system is sent to the cooling water boost pump 52.
The cooling water is returned to the cooling water boost pump 52 by two of the plurality of return pipes coming out from the lower part of the cooling water.

These two return lines are connected to connectors 80.82 attached to the anode stop plate 74. The anode and its cooling system will be described in detail in FIG. 3 below. plasma gun 16
are fitted with three separate cathode assemblies, described in detail below in Figure 4.5.

The individual cathode assemblies 1J84, 86.88 are generally cylindrical in shape, and the axis 90 of the cathode assembly is inclined at approximately 45 degrees with respect to the central axis 92 of the main body 70.
It is installed so that it penetrates the outer wall of 0. These three cathode assemblies 84, 86, 88 are typically connected to the gun body 70.
They are arranged evenly in concentric circles around every 120 degrees. The cathode assembly 84 is connected to the cooling water boost pump 52 in FIG.
Cooling water is taken from the tank. Similarly, cathode assembly 1J86
, 88 are each supplied with cooling water through supply pipes 94, 95. Cathode assembly with supply pipes 93, 94, and 95! The cooling water supplied to the J84.86.88 passes through the cathode assembly's internal cooling system, which will be described in detail below in FIG.

Each connector 96 is connected to the cooling water boost pump 52 via any one of the cooling water return pipes 79 . Another connector 98 attached to each side of the cathode assembly s4.86.88 is connected by piping (not shown) to the plasma gas source 54 in FIG.
Supplying plasma gas to the cathode assembly. Although the plasma gun 16 is shown in FIG. 2 as consisting of three cathode assemblies 'J84.86.88, this is for ease of understanding through the diagram, as will be explained later, and of course is not intended for the purposes of the present invention. According to the principle, it is also possible to construct cathode assemblies other than three, and the angle of the axis 90 of the cathode assembly with respect to the central axis 92 of the main body 70 is also 45°.
Anything other than that is fine.

As shown in FIG. 2, plasma source 46 is comprised of three separate plasma power supplies 99A, 99B, 99C connected to cathode assemblies 84, 86, 88, respectively. Plasma power supply 99A, 99B,
99C each have an individual DC power supply, the anode terminal of which is connected to the anode inside the gun body 70, and the cathode terminal of which is connected to the corresponding cathode assembly 84.
Connected to ゜86.88. Plasma power supply 99A, 99
B.

99C is independently power adjustable and therefore the cathode assembly! The power supplied to J84.86.88 can also be changed independently. As shown in Figure 2,
A variable polarity transitional arc power source 50 is connected between the anode within the body 70 and the process component 24 .

Although not shown in FIG. 2, a high frequency power source 48 is connected to the cathode assemblies 84, 86.88, preferably one to each cathode assembly 1J84, 86.88;
A plasma transfer arc is initially generated by superimposing a high frequency potential on the plasma power sources 99A, 99B, and 99C.

FIG. 3 is a partial cross-sectional view of the body 70, also depicting a portion of the cathode assembly 84 of the plasma gun 16. Cathode assembly! J86 and J88 are omitted to simplify the figure.

As shown in FIG. 3, the main body 70 has a substantially cylindrical shape, and has a cylindrical inner hole 100 at its center, which penetrates the main body 70 from the top surface 102 to the bottom surface 104.

An anode assembly 106 is attached to the lower portion of the inner hole 100. The anode assembly 106 is secured by an anode holder 108 attached to the bottom surface 104 of the main body 70.
It is fixed to the lower end of the inner hole 100.

The anode holder 108 will be described in detail later in FIG. 28.

The anode connection plug 110 forms part of a powder supply component attached to the upper part of the bore 100. The anode connection plug 110 extends upwardly from the top surface of the anode assembly 102 and fits into a hole 112 drilled in the center of the anode connection plate on the top surface 102 of the body 70 .

The anode connection plug 110 has a flange 114 at its lower end, and this flange 114 is connected to the inner surface 1 of the inner hole 100.
It has expanded to 16. The anode connection plug 110 has a substantially cylindrical hole 118, into which the powder supply tube holder 1, 20 is attached. Powder supply tube holder 120
has a thread cut on its top and an anode connection plug 110
It is secured by a screw at the top end of the . Further, the powder supply tube holder 120 is provided with a cylindrical hole 122 therein, and the powder introduction tube 72 is attached to the hole. As previously mentioned, the powder introduction tube 72 serves to direct metal powder or other thermal spray material from the powder feeder 20 shown in FIG. 1 to the plasma jet.

Metal powder or other thermal spray material is fed under pressure into plasma gun 16 through powder introduction tube 72 . As shown in FIG. 3, the tip of the powder introduction tube 72 is connected to the powder introduction port 12.
4, and power is distributed inside the cylindrical hole 118 provided in the anode connection plug 110. A clamp 126 inserted into the top 128 of the anode assembly 106 is
As will be described in detail later in FIGS. 29 to 31, the upper part 132
has a hollow, substantially cylindrical shape, and is provided in the anode connection plug 110 adjacent to the powder inlet 124.
It is attached to the lower part of 18.

The lower side of the clamp 126 has a hollow, generally cylindrical shape and is located at the top 128 of the anode assembly 106 .

As will be described in detail later in FIG. 15, the powder inlet tube holding part 136 is connected to the upper part of the clamp 126 in order to receive the powder inlet 124 therein. On the other hand, the lower part of the powder input tube holding part 136 extends into the anode assembly 106, and the tip thereof is connected to a cylindrical powder input tube 138. The powder introduction tube 72 has a hole 140 opened therein.
It connects to a central hole 142 provided in the powder inlet 124 to feed the powder. Further, the center hole 142 is connected to a center hole 144 provided in the powder input tube holding part 136 to feed the powder. As will be discussed in more detail below, a central hole 144 in the powder input tube retaining piece 136 delivers powder to one or more powder input ports provided within the powder input tube 138. In FIG. 3, the powder inlet tube 138 is provided with one powder inlet 146, which is further connected to a gas mixing chamber 148 made in the body (20> 150) of the anode assembly 106. connected to.

A gas mixing chamber 148 provided in the body 150 of the anode assembly 106 is connected to a nozzle portion 152 and is open to the outside of the plasma gun 16 at the bottom 130 of the anode assembly 106 . Further connected to the gas mixing chamber 148 are three arc chambers 154, each corresponding to a cathode assembly 84, 86, 88. Here, these arc chambers 154 are created within the body 150 of the anode assembly 106.

FIG. 3 shows arc chamber 1 corresponding to cathode assembly 84.
One of the 54 is depicted.

The main body 70 of the plasma gun 16 has a substantially cylindrical space 15.
6 is provided, into which a cathode assembly 84 is fitted. This cylindrical space 156 is indicated by a broken line in FIG. Usually, the end of this cylindrical space 156 is connected to a cylindrical hole 158,
Furthermore, this hole 158 reaches into the main body 70. This hole 158 is shown in dashed and solid lines in FIG. Furthermore, an insulator 160 is placed in this hole 158.
is fitted. Insulator 160 has cathode tip 162 mounted therein and is one of the components of cathode assembly 84 . Insulator 160 stops in arc chamber 154 and cathode tip 162 extends into arc chamber 154 . Although not shown in Figure 3, the cathode assembly & 6.88 are also included in plasma gun 1.
6 can be attached in the same way. As will be described later, the cathode assembly 84 includes a cylindrical hole 1 provided in the insulator 160.
The inert gas functions to flow in a spiral shape along a gas flow path 164 created by the annular space between the inner wall 166 of the cathode 68 and the cathode tip part 162. Plasma power supply 99A, shown in FIG. 2, is connected between cathode tip 162 of cathode assembly 84 and body 150 of anode assembly 106 to apply the necessary potential difference therebetween. By applying this potential and further flowing an inert gas around the cathode tip part 162, a plasma arc is generated in the arc chamber 152.
As a result, a plasma stream is formed in the gas mixing chamber 148.
, further flows through the nozzle portion 152 and is ejected from the plasma gun 16.

The velocity of the inert gas within arc chamber 154 is in the subsonic region. As the gas enters the central gas mixing chamber 148,
The gas mixes with the powder introduced through powder input tube 138. The gas mixing chamber defines a region within which the velocity of the plasma flow is the speed of sound. The gas and powder mixture is accelerated in a nozzle section 152 that defines a supersonic region of the plasma stream.

The plasma stream exiting the nozzle section 152 continues to the processing component 24 and reaches the collector cone section 14 at the bottom of the vacuum chamber 10 at supersonic speed according to the operation of the vacuum pump 42 shown in FIG.
I'm leaving. A transitional arc is generated between process component 24 and anode assembly 106 by a switchable transitional arc power supply 50 shown in FIGS.

Although not shown in FIG. 3, cathode assemblies 86 and 8
8 operates in a similar manner in conjunction with a corresponding arc chamber 154 in the body 150 of the anode assembly 106 to produce a plasma stream that flows from the gas mixing chamber 148 through the nozzle portion 152 and out of the plasma gun. can be done.

FIG. 3 shows the portion of an anode assembly 840 housed within the body 70 of the plasma gun 16 in solid and broken lines. On the other hand, FIG. 4 shows a portion of the anode assembly extending outside the main body 70, and FIG. 5 shows a cross-sectional view of the entire cathode assembly 84.

As seen in FIG. 4, the cathode assembly is segmented and configured as a cylindrical body as an extension 90 of the axis of the cathode assembly 84. The divided structure of the cathode assembly allows for internal pressure isolation and separation of the cathode assembly into 8 parts.
4 can be removed from the main body of the plasma gun 16 as an integral structure. Cathode assembly 84
is removably mounted within the body 70 such that the body 170 of the cathode assembly 84 fits and is received within the cylindrical space 156 shown in dotted lines in FIG. This is the insulating member 1 of the cathode assembly 84.
60 is a small cylindrical hole 1 in the body 70 so that the cathode tip piece 162 is set in the correct position within the arc chamber.
I will be seated in 58.

As shown in FIG. 4, the main body 70 of the plasma gun 16
The body 170 of the cathode assembly 84 that projects outwardly has a water connector 96 and a gas connector 98 . A cooling water pipe 93 supplied from the cooling water boost pump 52 shown in FIGS. 1 and 2 extends through an insulating nut 172 secured to the outer end of the main body 170. Cooling water enters the cathode assembly 84 through this line 93 and flows through the cooling system within the cathode assembly 84 through a water connector 96 coupled to one of the cooling water return lines 79 as described in connection with FIG.
The cooling water exits the assembly through the cooling water boost pump 52 . Also, as previously mentioned, inert gas from plasma gas source 54 shown in FIG. 1 is directed to gas connector 98.

In the cross-sectional view of the cathode assembly 84 shown in FIG. 5, the insulating nut screwed into the end of the cable insulation 174 through the screw 176 on the end of the cable insulation 174 is not shown. Also not shown is the water line 93 coupled to the connector 178 located in the cylindrical bore of the cable insulation. Cooling water from the cooling water boost pump 52 is supplied to the connector 178 by a water pipe 93, and the flow of the cooling water is indicated by an arrow 182 in FIG.

The cable insulation 174 is connected to the cathode assembly 84 along with the chamber insulation 160, the cathode coupling piece 184, which is typically cylindrical in shape and is made of insulation material, and the toroidal insulation retainer 186.
It forms part of the body 170 of. A cathode coupling part 184 made of an insulating material has a threaded section 188 at the end thereof and is threadedly connected to the cable insulation 174. The annular insulator holder 186 is located at the other end 192 of the cathode connection part 184 and is connected to the annular space 1 in the cathode connection part 184.
While fixing the chamber insulating material 160 to 94, bolt 1
93.

The cathode connecting part 184 has a cylindrical shape and is a hollow gas connecting pipe 19.
8 is seated in a cylindrical space 196. Gas connection pipe 1
98 extends from chamber insulator 160 along a portion of cylindrical space 196 . The remaining portion of the cylindrical bore forms a cathode connection tube 200. The cathode connection tube 200 is
The cathode assembly 84 is generally cylindrical and has a stepped profile.
It has a longitudinal axis coincident with the longitudinal direction 90 of. A cathode connection tube extends from a region located at one end 190 of cathode coupling piece 184 to a distal end of a region located at the outer end of chamber insulator 160 for attaching cathode tip 162 .

The outer diameter of the cathode connecting tube 200 is reduced by one step in a part of the gas connecting tube 198, and again by one step smaller in the chamber insulator 160, and the outer diameter is reduced by one step again in the chamber insulator 160. A circular tube-shaped space is formed on the inner wall of the tube. Such an annular space is the gas connecting pipe 19
8 and a uniform outer diameter that is less than the outer diameter of the first portion 208 that extends along a major portion of the length of the chamber insulator 160. A gas passage is formed by the second portion 210 held. Cathode connecting tube 200 has an annular edge extending into gas passage 206 located at the junction of first and second portions 208 and 210 of gas passage 206 .

The cathode connecting part 184 has a cylindrical bore 196 and an annular recess forming an annular gas introduction chamber 216 . The annular gas introduction chamber 216 surrounds the external portion of the gas connection pipe 198 and is connected to the plurality of small holes 21 of the gas connection pipe 198.
The other end of the gas connecting pipe 198 is connected to the inlet portion of the gas passage 206 through 8 . A plurality of small holes 218 are arranged in a circle around the gas connection pipe 198 in the annular gas introduction chamber 216, and one of the plurality of small holes 218 is shown in FIG.

A gas connector 98 attached to the outside of the main body 170 of the cathode assembly 84 shown in FIG. It is used to supply the inlet portion of the gas passage 206. A gas connector 98, not shown in FIG. 5, is connected to the annular gas introduction chamber 216 by a gas passage 220 of the cathode connecting part 184. Passageways 220 are shown in dashed lines in FIG. 5, and gas flow is indicated by dashed arrows 222. The gas flowing through the passage 220 fills the annular gas introduction chamber 216 and passes through the small hole 2.
18 into a first portion 208 of gas passage 206 . The gas in the first section 208 flows to the annular edge 212 of the cathode connection tube 200 where the gas flows through the gas passage 206.
A plurality of small holes 2 in the annular edge 212 in the second portion 210 of the
The arrangement of 18 forces a spiral flow pattern.

Details of the annular edge 212 are shown in FIG. 6.7, along with FIG. 7, which is a cross-sectional view of a portion of FIG.

As shown in FIG. 6, the annular edge has a plurality of small holes 224 arranged annularly at appropriate distances just outside the cathode connecting tube 200. As shown in FIG. As previously mentioned, connecting tube 200 has a longitudinal axis that coincides with the longitudinal axis of cathode assembly 84. The plurality of stomas 224 are arranged obliquely to the longitudinal axis 90, as can be seen in FIG. 7, which shows a cross-section of one of the plurality of stomas 224. This small hole 224, which is provided obliquely to the extension axis 90, serves as a gas passage through the annular edge 212 and forces the gas into a spiral pattern along the second portion 210 of the gas passage 206. be.

A swirling flow of inert gas is maintained through cathode tip 162 and into arc chamber 154 . Such swirling flow contributes to stabilizing the plasma arc formed within the arc chamber 154.

As shown in FIG. 5, the cathode tip part 162 is disposed at the tip of the cathode connecting tube 200 near the tip of the chamber insulating material 160. As shown in FIG. The cathode tip part 162 is made of tungsten or copper, and can be joined to the tip of the cathode connecting tube 200 by a method such as gold brazing, but it is preferably removed or threaded for ease of replacement. It is better to install it by In FIG. 5, the cathode connecting tube 200
The cathode tip part 162 is shown having a threaded part 228 at the tip thereof to which the cathode tip part 162 can be attached. As described above, cooling water is supplied from the cooling water boost pump 52 to the cathode assembly 84 via the piping 93. The pipe 93 passes through a threaded part 172 made of an insulating material, a cable insulating material 174, and is connected with a connecting part 178. Connecting parts 178
is located at the end 230 of the generally cylindrical connecting tube 232 within the cathode assembly 84 . The connecting tube 232 is disposed inside the cathode connecting part 184 made of an insulating material, extends into a space 236 inside the cathode connecting tube 200ρ, and has a screw cut at the end of the cathode connecting part 184 made of an insulating material. 234. The cathode connecting tube 232 connects to the water tube 2 at the tip.
38 is connected, thereby allowing cooling water to be supplied to the vicinity of the back surface 240 of the cathode tip part 162.

The cooling water is transferred to the connecting pipe 2 via the pipe 93 and the connecting part 178.
32, passes through the interior 244 of the water tube 238 at the tip of the connecting tube 232, is inverted near the back of the cathode tip part 162 in the interior space of the cathode connecting tube 200, and the water tube 238, the connecting tube 232 flowing outside. The flow of water in the figure is indicated by an arrow 246. The cooling water flowing outside the connecting tube 232 is guided to the annular space 250 inside the cathode connecting tube 200, and is further introduced into the drainage space 252 at an appropriate interval around the cathode connecting tube 200. It flows through a plurality of small holes 254 provided. Small hole 254
One of these is shown in FIG. The drainage space 252 is connected to a connecting piece 96 shown in FIG. 4, the path 256 to said connecting piece 96 being shown in FIG.

The gas path 220 and water path 256 used in the cathode connecting part 184 made of insulating material are shown by broken lines in FIG. The gas joint 98 and water joint 96 are easy to handle.

As mentioned in the description of FIG. 3, the modularized anode assembly 106 has an anode body 150, and as also shown in FIG. 8, the anode body 150 has a central axis 260. When the anode body 150 is attached to the anode assembly 106, the central axis 260 of the anode body 150 is aligned with the anode assembly 1.
06, and furthermore, the central axis 92 of the plasma gun 16 (Fig. 2).
matches.

The upper end 128 of the anode assembly 106 has a cylindrical space 262 with a threaded section 264 therein.

The threaded portion 264 is shown in FIG.
It accommodates the insertable clamp 126 shown in FIG. Below the threaded portion 264, the cylindrical space 262 tapers conically into a circular chamber 266, and the circular chamber 2
Reference numeral 66 has a structure to receive and stop the lower end of the raw material powder input tube support part 136 shown in FIGS. 3 and 5. Furthermore, the cylindrical small space 268 extends to the upper end of the anode gas mixing chamber 148, and is connected to the raw material powder input pipe 13 shown in FIGS. 3 and 15.
The structure is such that 8 is fixed. The lower end of the anode gas mixing chamber 148 is continuous with the anode nozzle section 152.

As mentioned above, in the second embodiment, the anode assembly 106 has three
The arc chambers 154 are equally spaced around the central axis 70 of the gun body. FIG. 8 shows one of the arc chambers. The arc chamber 154 continues to the bottom of an opening 274 in the side of the anode body 150. Opening 174 mates with the lower end of cathode insulator 160 during assembly of cathode assembly 84 into body 70 of plasma gun 16 .

This places the cathode tip 162 in the cathode assembly 184 in the proper operating position inside the arc chamber 154.

Arc chamber 154 extends along centerline 276 to gas mixing chamber 148 and is defined by a generally cylindrical space and a conical space 280 that expands into opening 274 .

The main body 150 of the anode assembly 106 has an annular cutout 282 surrounded by the lower bottom portion 130 of the anode main body 150 .

The cooling water in the anode cooling system is forcibly swirled through the annular cutout and through the plurality of small holes (28 in FIG. 8) provided between the arc chambers 154 of the anode body 150.
4.286) upwards and reaches the cylindrical space 262.

FIG. 9 is an external view of the anode assembly 106 viewed from the left side of FIG. 8 to show the opening 274 in the center. 10th
Illustrated is a top view of anode assembly 106 with opening 27
4 and the arc chamber 154 connected thereto are partially cut away. Actually the anode assembly 106
There are two more similar openings in the cathode assembly! 786.
88, but not shown in Figure 9.10. There is an annular protruding rim 288 at the bottom of the anode body 150, and the rim 288 is attached to the anode body 15.
When the anode 0 is attached to the gun body 70, it is seated in the recessed part 290 at the lower end of the cylindrical space 100 inside the gun body, allowing accurate positioning and preventing upward displacement of the anode body.

The anode holder 108 constitutes the bottom of the gun body 70, and the annular flange 109 attached to the anode holder 108 forms the third
It abuts the lower end of rim 288 and holds anode assembly 106 as shown.

FIG. 11 shows the arc chamber 15 of the anode main body 150.
4 is a sectional view showing the positional relationship between the gas mixing chamber 148 and the nozzle part 152. As mentioned above, the arc chamber 15
4 is a conical space 1IJff containing the cathode tip 162;
280 and a cylindrical space 27 connected to the gas mixing chamber 148
Consists of 8. The inert gas swirls around the cathode tip 162 and enters the gas mixing chamber 148 via the arc chamber 154.

The arc chamber 154 forms a discharge space between the anode body 150 and the cathode tip 162 in which a plasma arc is generated. The shape of the plasma arc changes depending on the pressure and amount of the swirling flow passing through the arc chamber 154, but the plasma arc passes through the arc chamber 154 from the cathode tip 162 and reaches the vicinity of the gas mixing chamber 148. The temperature of the plasma gas in the gas mixing chamber 148 changes depending on the arc arrival point. In addition, the swirling flow of inert gas directs the arc to the cylindrical space 278 of the arc chamber or the gas mixing chamber 1.
This has the effect of not concentrating on one point on the 48 walls, increasing the stability of the plasma arc.

Since the anode assembly 106 is modular,
It can be easily removed from the plasma gun 16. Therefore, by preparing anode assemblies 106 having different diameters and shapes for the arc chamber 154, it becomes possible to easily select and replace them according to the conditions of the plasma system to be used.

When operating the plasma gun 16, a cathode assembly is also required.
Central axis 2 of the anode assembly 106 of J84, 86.88
It is also possible to vary the angle relative to 60 to some extent. 11, the central axis 276 of the cathode assembly is aligned with the central axis 26 of the anode assembly 106.
It has an inclination of about 45 degrees from 0. In the present invention, this angle can be changed from 30° to 105°, but in reality, if it exceeds 45'', for example about 90°, the raw material powder introduced into the gas mixing chamber 148 will adhere to the inner wall of the gas mixing chamber 148. was recognized.

FIG. 11 also shows four different arrangements of the arc chamber 154. Among these, the one shown by the solid line has the widest scope of application in the embodiment, but other arrangement examples are also effective in other applications.

In the next embodiment, the cylindrical space 278 of the arc chamber 154 is arranged, but as shown in FIG. 296, - They are approaching each other as shown by the dotted chain line 302. Along with this, the cathode tip 162 also moves along the broken line 2 in the figure.
98, - arranged as shown by the dotted chain line 304.

Furthermore, in the case of the dashed line 302, there is also an embodiment in which the shape of the cathode tip 162 is made thin as shown by the broken line 306.

In the gas mixing chamber 148 of the present invention, the plasma gas flows through the nozzle portion 1.
It plays a role in guiding the raw material powder from the powder input hole 146 to a state below the speed of sound before being accelerated to supersonic speed at step 52. Raw material powders with different physical properties have different melting points, so in order to introduce them into the appropriate temperature range of the plasma gas,
It is desirable to be able to vary the length of gas mixing chamber 148.

By selecting the appropriate length of the gas mixing chamber 148, it is possible to prevent unmelted particles and powder from adhering to the inner wall of the gas mixing chamber 148 or the nozzle section 152. Anode assembly 106
is modular and can be easily replaced, so if you have several types with different lengths of the gas mixing chamber 148, you can select as appropriate.

The shape of the gas mixing chamber 148 also affects the thermal spray pattern of the raw material powder introduced. Usually, the spray pattern has a triangular shape corresponding to the positions of the three anodes.

Figure 12.13.14 shows three different gas mixing chambers 1
48 and the shape of the nozzle portion 152 following it are shown.

Fig. 12 is almost the same as that shown in Fig. 3.8.11 etc., and Fig. 13 shows that the length of the gas mixing chamber 148 is longer than that in Fig. 12, so it is relatively longer. The nozzle part is short. In FIG. 14, the length of the gas mixing chamber 148 is intermediate between that in FIGS. 12 and 13, and the nozzle portion 1
52 is divided into two parts 308 and 310. The nozzle top 308 extends at an angle from the lower end 272 of the gas mixing chamber to the upper end 312 of the nozzle bottom 310, and the nozzle bottom 310 extends at a constant angle to meet the lower end of the plasma gun bottom 130 at a greater angle than the nozzle top 308. Expands at an angle.

Although the powder input tube holding portion 136 is also shown in FIG.
In the figure, it is shown together with a powder input tube 138.

As shown in FIG. 3, the powder input tube holder 136 passes through the middle of the water flow guiding clamp 126 attached to the top of the anode assembly 106, and passes through the circular chamber of the anode body 150 as shown in FIG. It reaches 266. As shown in FIG. 15, the powder input tube holder 136 has an annular groove 314 in the upper part, which is not shown in the figure.
The clamp 12 has a structure in which QIJ is inserted.
The cooling water is sealed with the upper part 132 of 6. Similarly, the bottom groove 316 also seals the cooling water with the circular chamber 266 of the anode body 150 using an O-ring. As shown in FIG. 15, the powder input tube 138 has a threaded portion 318 on the outer periphery of the upper end and is screwed into the lower end of the holding portion 136.

The raw powder introduced through the powder introduction tube 72 and the powder introduction port 124 is introduced into the gas mixing chamber 148 of the anode assembly 106 via the center hole of the powder introduction tube holder 136. The powder inlet tube 138 can have various shapes as shown in FIGS. 16 to 25.

As mentioned above, the major feature of the present invention is that the plurality of cathode assemblies and anode assemblies are modularized.
Although it is easy to remove, the powder input tube 138 is also easy to replace and has a large degree of freedom in shape selection. Therefore, by changing the powder injection tube, the position at which the powder is introduced into the gas mixing chamber 148 can be changed.

The shape and diameter of the powder inlet can be changed as well as the material of the powder inlet tube 138. In accordance with the present invention, each of the three different arc chambers 154 is provided with a powder supply port, as will be described below. A powder input tube 138 equipped with a plurality of powder input ports of various shapes will be explained with reference to FIGS. 15 to 25. An important aspect of having separate and replaceable powder input tubes 138 is that the angles of the various powder input ports within each arc chamber can be varied to optimize the angles of the various powder input ports.

A combination of powder input tubes 138 is shown in FIGS. 16 and 17.

The case where there is one powder supply port is shown here.

As shown in FIG. 16, the powder input tube 138 is
A central hole 322 extending along the length of powder input tube 138 from an upper end 324 on the threaded side to a lower end 320 on the opposite side.
has. The central hole 322 extends from the threaded end surface 324 along the length of the powder input tube 138 to an intermediate portion 326.
It continues until Further, one powder inlet 328 is formed along the length of the powder inlet tube 138 from the portion 326 to the lower end surface 320. The end of the powder inlet 328 is formed by a conically shaped section 330. The powder inlet 328, including the conical part 330, is connected to the powder inlet tube 1.
It is provided coaxially with the central axis 332 of 38. center hole 3
22, when the powder input tube 138 shown in FIGS. 16 and 17 is installed inside the anode assembly 106, the central shaft 33
2 is the central axis 260 of the anode body 150 and the plasma gun 1
It coincides with the central axis 92 of the main body 70 of No. 6. Powder input tube 13
Since the lower end surface 320 of the gas mixing chamber 148 continues to the first end surface 270 of the gas mixing chamber 148, the powder fed to the center hole 322 of the powder input tube 138 flows along the central axis of the gas mixing chamber 148. The mixture is introduced into the mixing chamber 148. As best shown in FIG. 17, the lower end 32 of powder input tube 138
0 is a round concave groove 3 arranged at equal intervals around it.
It has 34.

In a plasma gun having a cathode divided into modules as described above, good results are obtained when powder is separately supplied to each arc chamber 154 through a plurality of powder inlets. Powder inlet 33 divided into three parts in Figure 18.19
6.338.340 shows the structure of the powder input tube 138. These three powder inlets 336, 338, 340 are shown in FIG. Powder supply port 338 depicted below
Only, the cross section is shown in FIG. These three powder inlets 336, 338.degree. 340 extend linearly from the terminal position 326 of the central hole 332 to the lower end 320 at relatively small acute angles with the central axis 332. The powder inlets 336, 338, 340 each connect to a dome 342 and terminate at the lower end 320. The powder input tube 138 shown in FIG. 18.19 is connected to the anode assembly 106.
When installed in the powder inlet 336.338.
340 connects to corresponding arc chambers near the portion where the gas mixing chamber 148 and the arc chamber 150 are in contact with each other.

When multiple powder inlets are applied to a plasma gun having a modular cathode, it has been found that the performance of the gun varies depending on the angle and size of the powder inlets. Since the powder injection tube 138 has the feature of being easily replaceable, there is an advantage that powder injection tubes 138 of various shapes can be selected when applied to various thermal spraying.

The arrangement shown in FIG. 20.21 is the same as that of FIG. 1819 in that the central hole 322 continues from the threaded portion 324 to a longitudinally central portion 344 of the powder inlet 138. . Beyond the central portion 344, the central hole 3
22 continues into the conical 346. Typically, three different powder inlets 348, 350, 352, equally spaced around the central axis 332, continue from the conical section 346 to the lower end surface 320 of the powder inlet tube 138. In the arrangement shown in FIGS. 20 and 21, a large part of the lower end 320 is formed by three relatively large cutouts 3.
54.356.358.

Powder inlet 348.350.352 is cut out part 354.3
56 and 358 continue to the part where it contacts the cylindrical side surface 360 of the powder input tube 138. Powder inlet 348.350
．． The terminal end of 352 is the conical part 33 in the case of Figures 16 and 17.
It does not end in a shape like the conical part 342 in the case of 0 or 18.19. Also powder inlet 348.350.3
52 makes an acute angle with respect to the central axis 332, which is greater than the angle of the powder inlet 336.338° 340 with respect to the central axis 332 in FIG.

In the case of the powder input tube 138 shown in FIGS. 22-23, the central hole 322 is shorter than that shown in FIGS. 16-21. The end of the center hole 322 is a portion 362.

Three different powder input ports 364 , 366 , 368 are equally spaced around the central axis 332 and continue from the end of the central hole 322 in the section 362 to the lower end 320 . The lower end 320 has three different cutouts 370372
, 374, powder inlets 364, 366, 368
continue into the cutouts 370, 372, and 374, respectively.

Powder inlets 364, 366, 36 shown in Figure 22.23
8 with respect to the central axis 332 is comparable to the angle with respect to the central axis 332 of the powder inlet 336, 338, 340 in FIG. 18.19. In the case of Fig. 22.23, powder inlets 364, 366, 368 are replaced by powder inlets 336, 338, 340 shown in Fig. 18.19 and powder inlets 20.21.
Powder input ports 348, 350 shown in the figure. than 352,
It has a relatively large diameter. As in FIG. 20.21, the powder inlet 364.3 shown in FIG. 22.23
66, 368 has no widening at the end, and the cutout 370.3
It continues until 72.374.

In the case of the powder input tube 138 shown in FIGS. 24-25, the central hole 322 continues along the length of the powder input tube 138 from the threaded end face 324 to the section 376.

Three different powder inlets 378, 380, 382 are arranged parallel and equally spaced around the central axis 332 and extend from the end of the central hole 322 near the section 376 to the powder inlet tube 1.
Three cutouts 384°3 in the lower end 320 of 38
86 and 388 respectively. Powder inlet 378
380, 382 have a relatively large diameter, as in the case of the powder inlets 364, 366, 368 shown in FIG. 22.23.

The greatest advantage of a multi-segmented electrode plasma gun, such as plasma gun 16 with a modular segmented cathode, is the greater increase in power level over a single cathode plasma gun. This increase in power level is possible by observing and adjusting the factors mentioned above, such as the presence of multi-segmented electrodes and the optimization of plasma systems with multi-segmented electrodes.

However, increasing power levels require greater cooling. This tendency is particularly noticeable with respect to the anode assembly, which is a common component of the entire plasma gun 16. Cathode assembly! The J84.86.88 is cooled by individual independent cooling systems as previously described in FIGS. 2 and 5.

Looking at FIG. 2, the cooling water boost pump 52 supplies cooling water to the connector 7678 attached to the anode stop plate 74 of the plasma gun 16 using two of the cooling water supply pipes 75. You can see that After the cooling water circulates through the anode cooling system to be described later, it is discharged through a connector 8082 and returned to the cooling water boost pump 52 using two of the cooling water return pipes 79.

FIG. 26 depicts the bottom surface of the anode stopper plate 74, and the connectors 76, 78°, 80, and
The 82nd position is indicated by a broken line. The connectors 76, 78 are mounted symmetrically with respect to the central axis 92, and each
It is connected to the bottom side of the anode stop plate 74 through 90 and 392. The connectors 80, 82 are mounted symmetrically with respect to the central axis 92 and are at a smaller distance from the central axis 92 than the connectors 76, 78, which are located at an angle of 90° therewith. , are connected to the bottom surface of the anode stop plate 74 through openings 394,396, respectively. Apertures 390 and 392
is an annular portion 3 sandwiched between two concentric grooves 400 and 402 provided on the bottom surface of the anode stopper plate 74.
It is located at 98. Grooves 400, 402 are each fitted with a seal 404, 406 as shown in FIG.

By attaching the anode stop plate 74 to the top surface 102 of the gun body 70, the seekers 404, 406 are attached to the anode stop plate 74.
The annular portion 398 is sealed from the portion outside the groove 400 and the annular portion 408 between the groove 402 and the center hole 112 on the bottom surface of the groove 400 . Opening 394 connected to connector 80.82
．． 396 is installed within the annular portion 408.

Figure 27 Gun body 7 when anode stopper plate 74 is removed
FIG. It can be seen that the top surface 102 of the main body 70 has a cylindrical hole 100 passing through the main body 70. The top surface 102 of the body 70 has screw holes 410 and 412.
414 are provided, and these screw holes are connected to the anode stop plate 74.
416, 418, and 420, respectively, and are perfectly aligned when the anode stop plate 74 is attached to the top surface 102 of the gun body 70. Through holes 416418, 4 provided in the anode stop plate
20 and screwed into the screw holes 410, 412, and 414 to fix the anode stopper plate 74 to the upper surface 102 of the main body 70. One such bolt 422 is shown in FIG.

Referring again to FIG. 27, the upper surface 1 of the gun body 70
02 is provided with an annular portion 424.

This annular portion 424 is connected to the bottom surface 104 of the main body 70 by three through-hole groups 426, 428, and 430, each consisting of three through-holes. Through hole group 4
A through hole 432, one of the through holes constituting 26, is shown in FIG. When the anode stop plate 74 is attached to the top surface 102 of the main body 70, the annular portion 424 perfectly matches the annular portion 398 on the bottom surface of the anode stop plate 74. Cooling water entering the gun body 70 via the connectors 76, 78 flows into the annular portion 424 through the through holes 390 and 392. Further, the annular portion 424
The cooling water then flows to the bottom surface 104 of the gun body 70 through the through holes 426, 428, 430.

The flow of cooling water in the through holes 432 and other paths is indicated by arrows in FIG.

FIG. 28 is a top view of the anode holder 108. The anode holder 108 has three holes 426, 438, 44 on the outer periphery.
0 is set. The anode holder 108 is assembled by passing bolts through the through holes 436, 438, and 440 and tightening them into screw holes provided on the bottom surface 104 of the gun body 70.
It is attached to the bottom surface 104 of the gun body 70. FIG. 3 shows how a bolt 442 is passed through a through hole 436 provided in the anode holder 108 and tightened into a screw hole 444. The anode holder 108 is attached to the bottom surface 104 of the gun body 70.
When the seal 446 is fixed to the third
As shown in the figure, it is in close contact with the bottom surface 104 of the gun body 70,
The annular portion 450 provided on the anode holder and the anode holder portion outside the annular portion 450 are sealed. The annular portion 450 occupies between the annular flange 292 and the annular wall 452, is disposed concentrically with the annular groove 448, and is connected to the through-hole groups 426, 428, 430 in the gun body 70. ing. The cooling water that has flowed downward through the through hole groups 426 428 and 430 flows into the annular portion 450 and surrounds the annular flange 292 . The annular flange 292 is the second
As shown in FIG. 8, grooves 454 are cut at an angle. The groove 454 is cut at an angle around the annular flange 292, so that the groove 454 is cut from the annular portion 450.
When the cooling water is pushed out through 4, the water flow becomes a swirling flow and is pushed out. 8, the anode assembly 106 includes an annular space 282 surrounding the bottom 130, and the anode assembly 106 includes an annular flange 292, as also shown in FIG. Cooling water is supplied in a swirling flow. In this manner, the cooling water flows while swirling, thereby maximizing heat exchange on the wall of the anode assembly 152 between the annular notch groove 282 and the nozzle portion 152.

The swirling cooling water in the annular cutout groove 282 is formed in the body 150 of the anode assembly 106 in FIG. 3 or 8.
It flows upward from the annular cutout groove 282 through water passages 284 and 286 shown in FIG. arc chamber 15
4, the passageway extends between the anode assembly 106 and the anode assembly 106 to provide better cooling at that location.

Once the cooling water reaches the top of the cavity, including channels 284 and 286, it typically flows into the lower portion 134 of the insertable clamp 126. FIG. 30 is a cross-sectional view of the insertable clamp 126 shown in FIG.
34 indicates that the inside has a large number of angled notches. Here, the water flow is swirled again so that the cooling water is led directly to the outside of the powder input tube holder 136 and sufficiently cools the powder input tube holder 136 there. This water flow that occurs in the annular passageway 458 formed on the inside 460 of the hollow structure of the insertable clamp 126 and on the outside surface of the powder input tube holder 136 is very important. This is because the powder inlet holder 136 can function as a heat sink. A large amount of heat generated within the gas mixing chamber 148 is transferred upwardly through a powder inlet tube 138 made of a material such as tungsten to a copper powder inlet retainer 136 which acts as a heat sink. The swirling flow in 458 is caused by the powder inlet holder 136
to provide the necessary large cooling effect.

As the cooling water continues to flow upwardly within the toroidal passageway 458 , it is directed through a number of passageways 462 and above the insertable clamp 126 . Such an insertion type clamp 12
Although not related to the central axis of 6, an upwardly angled small hole 462 is shown in the partial cross-sectional view of FIG. The cooling water flowing through the small hole 462 is connected to the upper part 132 of the insertable clamp 126.
It flows into an annular deep groove 464 located below the flange 114 of the anode connection plug 110.

FIG. 32 is a bottom view of the anode connection plug 110, showing the bottom surface of the flange 114. As shown in FIG. 32, the flange 114 has eight narrow grooves 466 arranged at approximately equal intervals around the flange. It flows into an annular passageway 468 formed by the outer surface 470 of the plug 110 and the cylindrical bore 100 of the gun body 70 .

Cooling water flowing through the annular passage 468 flows upwardly into an annular space 472 at the upper end 102 of the gun body 70 .

An annular space 472 surrounding the cylindrical inner surface 100 is located adjacent to the annular passage 408 on the lower surface of the anode connection plate 74 . As a result, the cooling water in the notch 472 flows through the hole 80.
and 82 to connectors 80 and 82. The cooling water is supplied from the connectors 80 and 82 to the cooling water boost pump 520.
The cooling water returns through two return pipes 79.

As shown in FIGS. 2 and 26, the connector 76
2 is approximately 90° away from the connector 82.

However, for convenience of illustration, connector 76 is shown in FIG. 3 as facing connector 82 on a straight line passing through central axis 92.

The plasma gun 16 has been described above in connection with the supply of powdered thermal spray material. It is a well known technique to introduce metals and other materials into the plasma stream to be sprayed in powder form. It is relatively long because the thermal spray material is powdered. In addition, it becomes possible to supply the plasma to an appropriate location within the plasma gun, which sometimes has a winding supply path. For example, a plasma gun having one cathode coaxially located above the anode has a complicated structure in which powder is supplied from the side of the plasma gun.

Although powdered metals and other materials are relatively easy to handle and suitable for feeding into a plasma gun through long and winding feed channels, the need to feed such materials in powdered form is a disadvantage. There are also some points. For one, materials such as metals are difficult and expensive to produce in powder form. Also, after manufacture, such powdered materials require special handling to minimize oxidation and the like. For this reason, it would be advantageous if the thermal spray material could be introduced in liquid or molten state. Such an approach is easily accomplished with a plasma gun having a modular cathode with material fed through the center of the gun at the top of the anode assembly. This allows the use of relatively short, direct material feeding equipment and minimizes the risk of solidification of molten material in the feed channel.

FIG. 33 is an example of an apparatus that can be used to spray metals and other materials in the molten state in connection with the invention.

The apparatus shown in FIG. 33 includes a metal melt feeder 474. Melter 474 includes powder tube 72 in plasma gun 16;
It is designed to be installed in place of the powder tube support 120, powder port 124, powder input tube holder 136, and powder input tube 138. The metal melt feeder shown in FIG. 33 has a feed tube support 476 similar in shape to the powder feed tube support 126 shown in FIG. Feed pipe support 4
76, when installing the support 476 on the plasma gun 16,
It has a threaded top 478 that mates with the threaded portion of the anode connection plug 110. When the feed tube support 476 is installed on the anode connection plug 110, the lower end 480 of the hollow feed tube 482 attached to the hollow cylindrical insulator 484 inside the feed tube support 476 is attached to the feed tube support. It extends downward from the lower end 486 of 47B. The lower end 480 of the hollow feed tube 482 passes through the cylindrical restriction 268 of the anode assembly 1060 to the first end 270 of the gas mixing chamber 148 .

The upper end 488 of the hollow feed tube 482 terminates in a cylindrical feed tube connector 490 having a crucible 492 therein.

A hollow, cylindrical crucible 492 is disposed within the supply pipe connector 490 , and the supply pipe connector 490
An annular passage 494 is formed with an inner wall 496 of the inner wall 496 . The lower end 498 of the annular passage 494 is connected to the upper end 498 of the hollow feed pipe 482.
Continues until 8. The pipe port 500 is the lower end 5 of the hollow supply pipe 504.
02, it partially extends to the hollow interior of the crucible 492. Tube port 500 seats at the upper end of supply tube connector 490.

Hollow supply tube 504 terminates at its upper end 506 to receive a plug 508 therein.

A gas connector 510 is connected to plug 508.

A plug 508 with a gas connector 510 can be removed from the top of the hollow supply tube 504 to supply material to the interior of the hollow tube 504 . From the upper end 506 of the hollow tube 504, (55
With plug 508 removed, the interior of hollow supply tube 504 is filled with solid metal or other material to be sprayed. Plug 508 is then placed back on the top end of the donor tube and power is applied to warm the metal in tube 504. The power is provided by a DC power source connected to electrodes 514 and 516. Electrode 516 is connected to hollow feed tube 482 between the top of feed tube support 476 and the bottom of feed tube connector 490.

Although the electrodes 514 and 516 are shown in an exaggerated and large shape in FIG. 33, they are actually much smaller so that the metal melt supply device 476 can be installed in the plasma gun 16. The same can be said for electrode 518. The electrode 518 is connected to the lower end 502 of the hollow tube 504. A DC power source 522 is connected between the electrode 518 and the anode body 150.

A DC power source 512 is connected to electrodes 514 and 516 to generate sufficient heat to melt a solid piece of metal within hollow tube 504. When this DC power source is connected to the electrode 518 and the anode body 150, molten metal is supplied from the hollow tube 504 through the crucible 492 and the hollow feed tube 482 to the gas mixing chamber 148 in the anode assembly 106. Provide sufficient heat to prevent solidification during drying.

The solid pieces of metal in the hollow tube 504 are melted as electric current is applied by the DC power source 512, and the molten metal flows downward through the mouth tube 500 and into the crucible 492.

Although the crucible 492 is filled with molten metal, the molten metal overflows the crucible 492 due to the action of the gas pressure transmitted by the gas mixing chamber 148 of the anode assembly 106 and does not flow into the annular passageway 494.

As previously discussed, gas pressure is created in gas mixing chamber 148 by introducing an inert gas into cathode assemblies IJ 84, 86, and 88 to form a positive arc and plasma stream. This gas pressure is transmitted through feed tube 482 and annular passage 494 to the top of crucible 492, where it prevents molten metal from overflowing from the crucible.

As a result, the molten metal remains molten until it is desired to be fed into the gas mixing chamber 148 of the anode assembly 106.

When feeding molten metal from crucible 492 into gas mixing chamber 148 of anode assembly 106, gas pressure is applied to hollow tube 5.
Pressure is applied to the upper end of 04. Although not shown in FIG. 33, the gas supply line is connected to the gas connector 5 at the upper end of the plug 508.
10 is connected to a source of inert gas such as argon.

Supplying argon gas inside the hollow tube 504 at the top end 506 counteracts the effects of the pressure from the gas mixing chamber 148, causing the molten metal in the crucible 492 to overflow and pass through the annular passageway 494. It flows down through the inner lower end 498 of feed tube 482 . The molten metal is in the hollow feed pipe 48
2 and into a gas mixing chamber 148 in the anode assembly 106 where it mixes with the plasma stream. DC power supply 522 provides sufficient power to prevent unwanted solidification of the sprayed metal as it flows through the path.

If it is desired to limit the delivery of molten metal to the gas mixing chamber 148 in the anode assembly 106, the supply of argon gas to the gas connector 510 is limited. As a result, the molten metal is again moved into the crucible 492 by the gas pressure in the gas mixing chamber 148.
It cannot overflow from the upper end, and an equilibrium state is brought about.

〔Effect of the invention〕

As described above, compared to conventional plasma generators, the present invention allows raw material powder to be introduced into the center of the anode in the flow direction of the plasma jet without powder adhesion, resulting in a higher yield of film formation on the target object. In addition, the present invention provides a plasma generating device that can be easily manufactured to a high output due to an effective water-cooling structure, etc.

In addition, the selection range of raw material powder can be greatly expanded by branching the end of the powder input tube.

[Brief explanation of drawings]

FIG. 1 shows a block diagram of the entire plasma system including the plasma generator of the present invention and a perspective view of the vacuum chamber. FIG. 2 shows an assembled external view of the plasma generator of the present invention. FIG. 3 shows a cross-sectional view of the plasma generator shown in FIG. 2, and shows the structure of the modularized anode, cathode, and powder-free tube. FIG. 4 shows an external view of the modularized cathode. FIG. 5 shows a cross-sectional view of the cathode of FIG. FIG. 6 is a side view from the direction of the cathode tip in FIG. 5, and a swirling flow is formed around the cathode by small holes arranged concentrically through which inert gas is introduced. FIG. 7 shows a cross-sectional view of the component 212 of FIG. 6 through which the oblique small holes for generating the swirling flow are passed. FIG. 8 shows a sectional view of the anode with cutouts for the module cathode, powder input tube, cooling water passage, etc. FIG. 9 shows a front view of the anode shown in FIG. 8. FIG. 10 shows a top view of the anode shown in FIG. Figure 11 shows the positional relationship between the anode and cathode.
Two different cathode arrangements are shown. Figures 12, 13 and 14 show cross-sections of anodes with different nozzle geometries, with three different arc chamber and nozzle geometries shown in the figures. FIG. 15 shows a powder dosing tube holder with a removable powder dosing tube that is attached to the top of the anode. FIGS. 16 and 17 show a first embodiment of the powder input tube shown in FIG. 15, including a sectional view and a side view from the end face direction. 18 and 19 similarly show a second embodiment of the powder input tube shown in FIG. 15. 20 and 21 similarly show a third embodiment of the powder input tube shown in FIG. 15. 22 and 23 similarly show a fourth embodiment of the powder input tube shown in FIG. 15. 24 and 25 similarly show a fifth embodiment of the powder input tube shown in FIG. 15. FIG. 26 shows a bottom view of the anode stop plate 74 for incorporating the anode shown in FIGS. 2 and 3. FIG. FIG. 27 shows a top view of the gun body 70 into which the cathode, anode, powder injection tube, etc. shown in FIGS. 2 and 3 are incorporated. FIG. 28 shows a top view of the lower end plate 108 for incorporating the anode shown in FIGS. 2 and 3. FIG. FIG. 29 shows a cross-sectional view of the clamp 126 that forms swirling cooling water disposed above the anode shown in FIGS. 2 and 3. Figure 30 shows the line 30 of the clamp shown in Figure 29.
A cross-sectional view at -30 is shown. The cooling water forms a swirling flow through the diagonally penetrating small holes. FIG. 31 shows a top view of the clamp shown in FIG. 29. Figure 32 shows plug 1 for anode connection shown in Figures 2 and 3.
14 is shown. FIG. 33 shows an overall view (-thin sectional view) of an embodiment of an apparatus for charging molten raw material (molten metal, etc.) from the upper part of the anode instead of the powder charging tube. 10...Vacuum chamber 13...Top lid, 14.
...Lower lid, 16...Plasma gun, 24
...Processing parts, 70...Gun body, 72.
... Powder supply pipe, 74 ... Anode stop plate, 84.
86.88... Cathode assembly, 106... Anode assembly, 108... Anode holder, 120... Powder supply pipe holder, 124... Powder inlet, 126... Clamp,
136... Powder input tube holding part, 138... Powder input tube, 148... Gas mixing chamber, 154... Arc chamber.

Claims (1)

[Claims] 1. In a plasma system that operates in a reduced pressure atmosphere below atmospheric pressure, plasma generation is characterized by comprising a common anode and a plurality of cathodes arranged so as to surround the anode. Device. 2. In the plasma generating device according to claim 1, each cathode has an individual DC power supply between it and the electrically common anode,
A plasma generating device characterized in that it can be controlled independently and has a separate transitional arc power source between a common anode and an object to be sprayed. 3. In the plasma generating device according to claim 1, each cathode has a module configuration, and can be easily removed, and by replacing the cathode, the angle relative to the anode can be changed.
A plasma generator characterized in that the discharge distance can be easily changed. 4. In the plasma generating device according to claim 1, the anode forms a space in the center and forms a nozzle shape in the downstream direction;
A plasma generating device characterized in that each cathode is connected to a central space by a small space forming a discharge space. 5. A plasma spraying apparatus according to claim 1, wherein the spraying raw material is introduced through a small hole above the center of the anode space surrounded by a plurality of cathodes. 6. In the plasma generating device according to claim hole 5, the small hole through which the raw material is introduced into the intermediate space of the anode is formed into an easily replaceable sleeve, and by changing the sleeve,
A plasma spraying device that is characterized by the ability to input raw materials with any small hole diameter. 7. The plasma generator according to claim 6, characterized in that the tip of the small hole of the raw material input sleeve is branched into a plurality of parts, and by changing the branching angle, the raw material can be input to any position in the central space of the anode. Thermal spray equipment. 8. A plasma spraying apparatus according to claim 5, characterized in that a crucible or the like is provided above the center of the anode space, and the raw material is molten in the crucible or the like and then introduced into the anode space.